Gas barrier film is noticed as not only wrapping material for foods or medicine but also substrate of electronics devices, as the film is good in thinness, lightness and flexibility. Particularly, the film is noticed as the substrate for liquid crystal display or organic EL display which is looked for application to wall-hanging television or electronic paper. The gas barrier film is usually obtained by laminating gas-barrier layer on a transparent resin film substrate.
There are various suggestions concerning the gas-barrier layer. For instance, in patent document 1 or patent document 2 is described gas barrier film comprising an alternate laminate of inorganic films comprising inorganic oxide such as SiO2 and Al2O3, and films comprising resin such as polyarylate and polyacrylate. But, as the result of our review, the film has low adhesion between resin film and inorganic film, so we found that both films are easily peeled off. This peel-off may easily bring about a defect such as crack in the inorganic film, being to lower gas barrier property. The film comprising resin such as polyarylate and polyacrylate is high in water absorption, which results in releasing of water vapor and so on from the resin film when the inorganic film is formed, being to lower density of the inorganic film. Not less than eight layers of the inorganic film and the resin film are required to be enough gas barrier property, so it is dissatisfied with productivity thereof.
As other example, in patent document 3 is described to use hydrocarbon polymer having alicyclic structure for an organic film in gas barrier layered product of inorganic film and the organic film. As the polymer has low water absorption and little or no gas release, the polymer is considered to be favorable for the organic film of the above layered product. As the result of our review, however, use of only means for resolution described in patent document 3 is to result in insufficiency of adhesion between resin film and inorganic film yet.
On the other hand, organic EL device is looked for application to display such as segment display, dot-matrix display and liquid crystal display, or light source. There are organic EL device having SH-A structure that positive hole transport layer and luminescent-material layer are formed between hole injection electrode as electrode and electron injection electrode as negative electrode; organic EL device having SH-B structure that luminescent-material layer and electron transport layer are formed between positive hole injection electrode and electron injection electrode; organic EL device having DH structure that positive hole transport layer, luminescent-material layer, and electron transport layer are formed between positive hole injection electrode and electron injection electrode, as example of organic EL device.
In any structure of the organic EL devices, organic EL device works by principle that positive hole injected from positive hole injection electrode (positive electrode) and electron injected from electron injection electrode (negative electrode) are recombinated in interface of luminescent-material layer and positive hole (or electron) transport layer and in luminescent-material layer to emit light. Therefore, against an inorganic EL device having luminescence mechanics by collision excitation, an organic EL device has a feature which light can be emitted with low voltage and it is favorable for luminescence device in the future.
Example of structure of typical EL device is shown in FIG. 1. The organic EL device shown in FIG. 1 comprises transparent substrate 16, lower electrode layer 54, luminescent-material layer 62 and upper electrode layer 55. A conventional organic EL device having bottom emission mode, which light radiated in the luminescent-material layer 62 is sent out on the side of the transparent substrate 16, is small in an emission area, as a thin film transistor is put on the side of the transparent substrate. Top emission mode, which light radiated in the luminescent-material layer 62 is sent out on the opposite side of the transparent substrate 16 in view of the luminescent-material layer 62, can give enough area for emission, so it is looked recently.
However, in an organic EL device, using of material for negative electrode being low in work function easily causes the negative electrode to be corroded or oxidized by reacting with water-vapor or oxygen in air. This degradation of the negative electrode results in sprouting non-emission region called as “dark spot” in the luminescent-material layer, causing organic EL device to degrade in the property by aging.
Not only the material used in negative electrode, but also organic material used in luminescent-material layer, transport layer and so on is changed in structure by reacting with water-vapor or oxygen, which results in enlarging dark spot likewise.
In order to enhance endurance or reliability of organic EL device, organic EL device whole requires a seal to prevent organic material used in negative electrode, luminescent-material layer or transport layer from reacting with water-vapor or oxygen.
As to sealing of organic EL device, patent document 4 discloses the forming method of film of Si3N4, diamond like carbon or the like on the external surface of the organic EL device by ECR plasma CVD method. In the document is described that oxidization of electron injection electrode (negative electrode) can be prevented, and water-vapor resistance of the organic EL device can be improved by the forming method. But, the film made of the above material needs large thickness for improvement of water-vapor resistance, which causes elevating internal strain easily to make crack in film, being likely to reduce the sealing performance by contraries.
Patent document 5 discloses a method of sealing an organic EL device with a layered product of organic matter and silicon oxynitride. According to the method, an organic EL device having high reliability can be obtained by setting a close protection part having a thickness, which can prevent water-vapor, oxygen and so on from going in from outside and can completely restrain enlargement of dark spot, on the upper of the organic EL device. But, adhesion between organic matter and silicon oxynitride is extremely low without limitation of chemical structure or film making method, so the peel-off brings about defect in an interface to lower sealing property.
Also, the applicant has suggested, in patent document 6, a sealing film for organic EL device comprising decomposition polymer of per-fluoro olefin. According to the document, degradation of organic EL device by oxygen or water-vapor in outside can be restrained, so the device becomes so efficient and effective for producing light, and suitable to downsize or thin the device. But, applying of the decomposition polymer alone on the organic EL device results in having yet been insufficient sealing property, so it needs more improvement.    [Patent Document 1] JP-A-2003-206361    [Patent Document 2] JP-A-2003-48271    [Patent Document 3] JP-A-2002-234103    [Patent Document 4] JP-A-H10-261487    [Patent Document 5] JP-A-2002-25765    [Patent Document 6] JP-A-2002-56971